Confocal microscopes may employ small aperture objective lenses to improve depth of field at high magnifications. As a result, such confocal microscopes require high intensity light sources to provide sufficient specimen illumination for viewing or electronic imaging. Inorganic and some organic specimens can generally tolerate exposure to such high intensity light sources. However, many organic and most active biological samples cannot tolerate prolonged exposure to high intensity light sources. For this reason, modern researchers, particularly in the biotechnology field, have welcomed the introduction of wide field, optical sectioning microscopes employing wide aperture lenses. Due to the greater light gathering ability of these optics, active biological samples can be viewed for prolonged periods.
Some systems collect optical information from wide field optics electronically, such as in a charged coupled device array, to digitize and integrate that information over time, and to provide a computer generated three dimensional image of the sample. Such measurement techniques are particularly valuable in the field of florescence microscopy where images of the specimen are not only integrated over time, but wavelength as well.
Due to the unique nature of wide field microscopy, precise movement of the specimen along the optical axis, as well as in a plane perpendicular to the optical axis (hereinafter xe2x80x9creference planexe2x80x9d) is critical for the development of an accurate three dimensional image of the sample. The ability to move the sample in the reference plane, without inducing undesired motion along the optical axis is important for maintaining the sample in focus, as well as for the development of an accurate three dimensional representation.
Historically, confocal microscopes have not been burdened with the challenges of developing a three dimensional image of the specimen. Thus, movement of the specimen in the X and Y direction (i.e., the reference plane) does not present a problem even if undesirable and motion in the Z-axis (i.e., the optical axis) is induced. The microscope operator merely refocuses the image. Thus, microscope stages employing confocal technology typically employ independent frames or carriers which are moveable in the X-, Y- and Z-axis directions by manually operated, micrometer type devices. Such devices are not suitable for adaptation to computer control where a pre-established scanning pattern is imposed on the specimen to develop the desired three dimensional image.
Accordingly, it would be desirable to provide an orthogonal motion microscope stage which is capable of moving a specimen in the X-Y reference plane and Z-axis optical direction with high accuracy. The motion of the stage carriers or frames is preferably automatic and adapted for computer control.
A Z-axis stage for use in, e.g., an orthogonal motion microscope stage, includes a carrier plate, an actuator plate, and a base. Three or more upper camming elements with downwardly directed camming surfaces are mounted to the underside of the carrier plate using a semi-kinematic mounting technique. Three or more lower camming elements with upwardly directed camming surfaces are mounted to the top surface of the base using a semi-kinematic mounting technique. The semi-kinematic mounts include a hemispherical mount attached to the mounting surface and a cone receptacle in the component to be mounted. The actuator plate includes apertures to accommodate the lower camming elements and the upper and lower camming surfaces of adjacent camming elements are mated. Linear slides are interposed between the mated camming surfaces and the lower camming elements and the base. A linear actuator is used to move the actuator plate in an X-Y reference plane, and this motion is translated into movement of the carrier plate along the Z-axis (i.e., the optical axis) in response to the relative, sliding motion of the mated camming elements.